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I mean acceptance happens after host memory >>> allocation but they are not in lockstep, acceptance can happen much later. >> >> No, I meant reserving guest physical memory range from hypervisor e.g with >> RMPUpdate for SEV-SNP or equivalent at TDX side (PAMTs?). > > As proposed, RMP/PAMT updates will occur in the fault path, i.e. there is no way > for userspace to pre-map guest memory. > > I think the best approach is to turn KVM_TDX_INIT_MEM_REGION into a generic > vCPU-scoped ioctl() that allows userspace to pre-map guest memory. Supporting > initializing guest private memory with a source page can be implemented via a > flag. That also gives KVM line of sight to in-place "conversion", e.g. another > flag could be added to say that the dest is also the source. Questions to clarify *my* understanding here: - Do you suggest to use KVM_TDX_INIT_MEM_REGION into a generic ioctl to pre-map guest private memory in addition to initialize the payload (in-place encryption or just copy page to guest private memory)? - Want to clarify "pre-map": Are you suggesting to use the ioctl to avoid the RMP/PAMT registration at guest page fault time? instead pre-map guest private memory i.e to allocate and do RMP/PAMT registration before running the actual guest vCPU's? Thanks, Pankaj > > The TDX and SNP restrictions would then become addition restrictions on when > initializing with a source is allowed (and VMs that don't have guest private > memory wouldn't allow the flag at all). >